Stone saw



Patented Sept. 9, 1930 DANIEL FREDERICK MCGOVEBN, OF MONTPELIER, VERMONTSTONE SAW Application led lnly 16, 1929. Serial No. 378,748.

My present invention involves saws of the detachable tooth type andparticularly those intended for stone sawing. In such use the cutting iseffected by an abradantsuch as chilled shot and the use of such a mediumas is well known while involving a variety of difficulties is generallyapproved as the best known basis of general sawing operation.

One of the ditculties has been to provide saw teeth which would operatewith such a material as shot with the desired efficiency,

and a reasonable operating economy especially as to the triplel dilemmaof replaceability of the tooth, its strength when in place and itscheapness as an element of wear whlch must be frequently replaced.

In my previous Patent No. 1,690,544, I disclosed a' saw and saw tooth ofthis type and while not limited to that particular coni struction mypresent invention or discove being somewhat sequent thereto may be avantageously described by referencevto my said patent. I have thereforeshown in the accompanying drawings as'illustrative of my presentinvention a structure of the general type of my prior patent. In thesedrawings:

Fig., l shows broken apart two portions of such a stone saw, the upperportion before use, and the lower portion after use.

Fig. 2 is' an enlarged vdetail of tooth as-` sembly. i

Fig. 3 a somewhat exaggerated section on the arc 3-3, of 2, and

Fig. 4 is a diagrammatlc section illustrating the interlocking actionwhich occurs 41n the use ofthe saw. 1

I have indicated :at l a saw blade of con-v ventional type and at 2raplurality of de- 40 tachable and replaceable tooth units in accordancewith my invention and riveted or otherwise secured to the periphery ofthe saw blade as indicated at 3.

Each tooth is of generally rectangular shape presenting an outer orcutting edge 4 which. is developed on the arc of a circle substantiallyconcentric to the axis of vrotation of the saw blade, an inner orattaching edge 5 which is bifurcated to straddle the peripheraledge ofthe saw blade.`

Each tooth is notched between its front and rear edges, as indicated at8, to provide an abrasive pocket opening into the cutting edge 4 of thetooth, preferably at an angle thereto: As shown, the notches 8 arecurved 55 and lead from the vcutting edge 4 forwardly and inwardly, theresultant pocket thus being so shaped as to insure entrapment andretention of adequate abrasive therein.

I thus provide a blade with detachable teeth in which the front and rearedges of the teeth are radial to the axis of rotation of the disc (asindicated by the radius lines R, Fig. l) and are interlocked with eachother so as to present maximum strength and rigidity, and in which thecutting edge of each tooth is notched to provide a re-entrant abrasivepocket intermediate of said interlocked front and rear edges.

By my construction, I provide continuous cutting surface which can beworn ldown practically to the blade edge itself without appreciable lossof efficiency in cutting action.

The location of the abrasive pocket in the cut ting edge itself of thetooth insures that an adequate amount of abrasive will be maintainedbetween the cutting edge of the tooth and the bottom of the saw kerf'3so long as any of the cutting surface remains, and the front andrearedge interlocked of adjacent teeth reduces vibration anddisalignment of teeth as well as imparting peripheral strength andrigidity to the teeth series as a whole.

In my previous patent, above mentioned, I describe .a tongue and grooveconstruction for the sides of the teeth, so as to dovetail with thesimilar edges of the next adjacent teeth when the teeth are assembled onthe blade, thereby presenting a solid unbroken tooth series with no gapsor spaces between adjacent teeth. This resulted in increased ,rigidityand strength, and prevents buckling or twisting of the teeth out ofalinement with each other in the operation of the saw.

The cost of making the teeth with tongue and groove interlock was,however, considerable and only justified by the "satisfaction in result.The concept of my present inventionthen occurred. I had detected atendency in the teeth I had been using to burr or fin back on their rearedges. It seemed of no disadvantage but I then conceived the idea ofutilizing this tendency and provide ungrooved teeth which would becomeinter; locked in use by the very wear of their usage,

According to my present invention I have my teeth substantiallystraight-sided and on substantially a radial line and assemble them asclosely adjacent as is convenient. In this tolerance of assembly I alsogain a great advantage. To assemble teeth on the periphery of a largesaw there is much diliiculty ifv the interlock of tongued and groovedsides has to be considered. Slight variances in dimension multiplyrapidly at the periphery. Furthermore, the replacement of an odd toothbroken by accident was often troublesome.

My present invention gives a wide tolerance and makes assembly andreplacement easy and saves valuable time in shut down. I have indicatedon the drawing the forward edge of my tooth 2 at 6 and the rear edge at7. These, however, must not be confused with my prior patent. Inpractice the contourA of these edges may be disregarded7 although asshown in Fig. 4, the forward edge 6 is preferably (and usually is) notan absolutely square cutedge.

Here again I utilize a tolerance or what Aeven mightv be otherwise acrudeness to attain a most 'advantageous result.

As indicated in Fig. 4 the lack of sharp corners on the edge 6 is anadvantage. In practice I blunt these corners' as in Fi 4. Thisfacilitates and hastens the interloc indicated in Fig. 3, which iseffected by the action of the shot S retarded by the wall W of the kerf.This action spins or draws the relativel soft metal of the tooth toproduce the overlapping fin F which draws over the edge 6 of eachsucceeding tooth.

In this way I provide for a tooth interlock which becomes more and moreeective until under usage instead of wearing out as in the case ofdependence of previously provided tongue and groove, there is a constantphysical metallic confluence between the teeth so that as indicated inthe lower part of Fig. 1 the teeth become in effect an integral orphysicall autogenously welded band on the bla e 1.

This opens up a new phase of usefulness for the straight or radiallysided saw tooth of whatever type or shape. Its economies and advantagesare obvious to all familiar with its art and protection is claimedaccordingly.

What I therefore claim and desire' to secure by Letters Patent is 1. Ina stone saw adapted to be used with :in abradant, a blade having aplurality of adJacent teeth, said teeth being formed of ductile metaland having their opposing edges unchanneled and normally spaced apartfrom each other distances not greater than the limits of ductileextensibility of the teeth whereby the action of the abradant retardedin the saw kerf causes the teeth to spin or draw into interlock witheach other in the use of the saw.

2. In a rotary stone saw adapted to be used with an abradant, a blade,and a plurality of inserted teeth secured to said blade, said teethbeing .formed of ductile metal and having substantially radialunchanneled opposing edges normally spaced apart from each otherdistances not greater than the limits of ductile extensibility of theteeth whereby the action of the abradant retarded in the saw kerf causesthe teeth to spin or draw into interlock with each other in the use ofthe saw.

In testimony whereof I ahx my signature.

DANIEL FREDERICK McGOVERN.

